Due to the rising cost of liquid fuel (e.g., diesel fuel) and ever increasing restrictions on exhaust emissions, engine manufacturers have developed dual-fuel engines. An exemplary dual-fuel engine provides injections of a low-cost gaseous fuel (e.g. natural gas) through air intake ports of the engine's cylinders. The gaseous fuel is introduced with clean air that enters through the intake ports and is ignited by liquid fuel that is separately injected during each combustion cycle. Because a lower-cost fuel is used together with liquid fuel, cost efficiency may be improved. In addition, the combustion of the gaseous and liquid fuel mixture may result in a reduction of harmful emissions.
In these dual-fuel engines, use of a gaseous fuel injector in addition to a liquid fuel injector may necessitate inclusion of one or more gaseous fuel control valves to control the flow of the gaseous fuel into the combustion chamber. However, operation of the control valves may result in residual gaseous fuel at one or more locations along a gaseous fuel pathway after the control valves close, such as in a gaseous fuel injection nozzle. Since the gaseous fuel injection nozzles may be a different shape than the air intake ports in which they are located, this residual gaseous fuel may leak from the nozzle after the valve closes. The leaked fuel can become undesirable waste or contaminate a subsequent injection event.
One method of handling the difficulties presented by fuel leaking from injection nozzles is described in U.S. Patent Application Publication No. 2014/0338633 (the '633 application) published in the name of Fern on Nov. 20, 2004. The '633 application describes a fuel injection assembly having a nozzle portion with a seal member that allows the nozzle portion to be secured within an injector aperture formed within a cylinder of an engine. The nozzle portion is provided with a tiered portion that allows the nozzle portion to fit various configurations of injector apertures of combustion chambers having various sizes.
Although the system of the '633 application may address some of the drawbacks associated with residual fuel located in fuel injection nozzles, it may not be adequate for all applications. For example, in systems that include a gaseous fuel injector located in an air box, it may not be practical to use a nozzle that encompasses the entire air intake port because this arrangement would prevent air from also being injected through the port.
The disclosed nozzle is directed to addressing one or more of the problems set forth above and/or other problems of the prior art.